Statistical analysis and volcano monitoring has established that there are both eruptions which were likely triggered by large earthquakes, and given us some plausible mechanisms for how this might happen, although this is still a rather rare event. Ron Schott brought up an interesting point in a comment, however: The mechanisms that I discussed are generally regarded as operating in the short-term – i.e., a few days to weeks after an earthquake (perhaps even a few months). But what about long-term earthquake triggering – are there connections between volcanic eruptions and earthquakes which happened years before? Are there any plausible mechanisms for long-term triggers, and how would they operate? I did a little research to see if I could find answers to either of these questions.

It turns out that there is even less known about the possibility of delayed eruption triggering than there is about short-term triggering. I could only find two papers that even discussed it, and one referenced the other. The initial paper, Remote seismic influence on large explosive eruptions (Marzocchi, 2001) found statistically significant links between eruptions and earthquakes on two timescales: 0-5 years and 30-35 years. Marzocchi suggests that the short-term link (and delay) could be “attributed to the inertia of the volcanic system in reacting to static stress changes” – in other words, it takes a little while for the mechanisms caused by stress changes to destabilize the volcanic system enough to cause an eruption. For the 30-35 year lag, however, Marzocchi doesn’t suggest any potential mechanisms, merely notes that the timescale is similar to the estimated relaxation time of a viscous asthenosphere. I’m not entirely sure if this is a plausible connection, or what mechanism would be associated with “asthenospheric relaxation”. (I guess it probably refers to long-term regional stress changes rather than immediate stress changes caused by the passage of seismic waves, but I could be wrong.)

The only other paper I could find which mentioned long-term triggering referenced the Marzocchi paper, with this comment:

“Prior studies did not find evidence for triggered response times longer than about five days, but this does not necessarily mean they do not occur. We might expect eruptions triggered after a longer delay to be less frequent than those triggered within days of an earthquake, with potential variability between arc settings. Thus, such events may not be detectible above the natural background variability of eruption rate in global data sets. Thus, while individual instances of delayed triggered eruptions have been proposed, demonstrating whether a general relationship between earthquakes and eruptions exists on timescales longer than a few days has proven difficult.”

In other words: There could be instances of long-term triggering of volcanic eruptions, but not only is it difficult to find many statistically significant instances, it will be very difficult to explain how the triggering happens. The “asthenospheric relaxation” idea seemed very offhand to me, but if anyone knows of a paper that explains how it could be related to eruptions, I’d be happy to update the post with additional info.

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Thanks for the post. With impeccable timing, Mark Bebbington and Warner Marzocchi have a paper in press at JGR which takes explicit account of the prior history of a volcano when developing a statistical model for triggering events:

Jessica: One other aspect to earthquake triggering. There is some talk about earthquakes being triggers for extracting liquid from crystal mushes, which might not directly lead to an eruption but does generate a body of crystal-poor, liquid and likely eruptible magma. Now, this is more speculation, but it has been mentioned:

I can’t remember the references, but I know I’ve seen talks at AGU that try to link the eruption of Chaiten with earthquakes as well – mostly as a way to mobilize extracted rhyolite. Too many papers … !

I’m not sure what you’re referring to with the crustal rebound question, but there are definitely instances of earthquakes triggering eruptions in the short term (the eruption of Japan’s Shinmoedake following the recent earthquake is most likely an example, and I’ve discussed mechanisms in last week’s post on short-term triggers).

Here as elsewhere, Charles Darwin can claim priority.* In his valuable comment on the Southern Chile earthquake of February 20, 1835, he observed that two volcanoes “in the Cordillera in front of Chiloé . . . burst forth at the same instant in violent action” while Villarica Volcano, much closer to the epicenter, “was noways affected”.

The 8.8 Chile quake of 27 Feb 2010 may have caused a swarm of shallow quakes 10,000 K away in central California, as well as a cluster of deep, low-frequency quakes on the San Andreas Fault.

Reference: Research Spotlight: AGU’s Eos, 8 Feb 2011.

My supposition
Those quakes, triggered in close harmony, may be influenced by one of two 180 lat. opposed, north penetrating pressure points; situated on the Antarctic Plate. One is near East 90 Ridge. The other is near West 90 latitude. Both rise to Tropic of Capricorn.

One points up roughly towards Burma Plate, The Antipode latitude’s other pressure points roughly along South America’s west coast sub-duction zone, ending by transferring its force around and past the Nazca Plate through the San Andreas Fault region near to Pacific Plate’s east boundary. (Above the Nazca plate. To the east is Haiti’s horizontal faults: Those combined focal point may be the; pushed around; landing zone of the dinosaur killer.)

Consider: Northern hemisphere holds more land mass than south’s: inferring Earth’s centrifugal force pushes portions of North’s mass against those pressure points; which all aids two other forces.

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About Jessica

Jessica Ball is a Mendenhall Postdoctoral Fellow at the U.S. Geological Survey, researching stratovolcano hydrothermal systems and how they affect volcano stability. She previously worked at the Geological Society of America's Washington DC Policy Office, learning about the intersection of Earth science and legislative affairs. Her PhD in volcanology focused on how water affects the stability of cooling lava domes, and involved both field investigations and numerical modeling applications. Her blogging covers a range of topics, from her experiences in academic geosciences to science outreach and communication to her field and lab work in volcanology.

Ideas and opinions expressed on this site are those of the authors and commenters alone. They do not necessarily represent the views of the American Geophysical Union.